Noise attenuation unit for engine systems

ABSTRACT

Noise attenuation units are disclosed that are connectable in a system as part of a fluid flow path. Such units include a housing defining an internal cavity and having a first port and a second port each connectable to a fluid flow path and in fluid communication with one another through the internal cavity, and a noise attenuating member seated in the internal cavity of the housing within the flow of the fluid communication between the first port and the second port. The noise attenuating member enables the fluid communication between the first port and the second port to flow through the noise attenuating member.

RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.14/565,075, filed Dec. 9, 2014, which claims the benefit of U.S.Provisional Application No. 61/913,668, filed Dec. 9, 2013 and U.S.Provisional Application No. 61/971,008, filed Mar. 27, 2014.

TECHNICAL FIELD

This application relates to noise attenuation in engine systems such asinternal combustion engines, more particularly to the inclusion of aporous member in a housing configured for insertion in a fluid flow pathof an engine.

BACKGROUND

Engines, for example vehicle engines, often include aspirators and/orcheck valves. Typically, the aspirators are used to generate a vacuumthat is lower than engine manifold vacuum by inducing some of the engineair to travel through a Venturi. The aspirators may include check valvestherein or the system may include separate check valves. When the checkvalves are separate, they are typically included downstream between thesource of vacuum and the device using the vacuum.

During most operating conditions of an aspirator or check valve, theflow is classified as turbulent. This means that, in addition to thebulk motion of the air, there are eddies superimposed. These eddies arewell known in the field of fluid mechanics. Depending on the operatingconditions, the number, physical size, and location of these eddies arecontinuously varying. One result of these eddies being present on atransient basis is that they generate pressure waves in the fluid. Thesepressure waves are generated over a range of frequencies and magnitudes.When these pressure waves travel through the connecting holes to thedevices using this vacuum, different natural frequencies can becomeexcited. These natural frequencies are oscillations of either the air orthe surrounding structure. If these natural frequencies are in theaudible range and of sufficient magnitude, then the turbulence-generatednoise can become heard, either under the hood and/or in the passengercompartment. Such noise is undesirable and new apparatus are needed toeliminate or reduce the noise resulting from the turbulent air flow.

SUMMARY

In one aspect, noise attenuation units are disclosed that areconnectable in a system as part of a fluid flow path. Such units includea housing defining an internal cavity and having a first port and asecond port each connectable to a fluid flow path and in fluidcommunication with one another through the internal cavity, and a noiseattenuating member seated in the internal cavity of the housing withinthe flow of the fluid communication between the first port and thesecond port. The noise attenuating member enables the fluidcommunication between the first port and the second port to flow throughthe noise attenuating member. In one embodiment, the first port and thesecond port are aligned opposite one another.

In another embodiment, one or more of the first port and the second portincludes an elbow. The portion of the housing having the elbow ispositionable for sealing attachment to the other portion with the elboworiented at any angle in a 360 degree radius relative to the portincluded in the other portion. In one embodiment, one of the first portand the second port enters the internal cavity from the top or thebottom of the housing and the other enters from a side of the housing,and optionally includes the elbow. Also, whichever of the first port andthe second port enters the housing from the side is typically offsetfrom the center of the housing.

In one embodiment, the noise attenuating member comprises a porousmaterial. Additionally, the noise attenuating member may include one ormore bores therethrough aligned for fluid communication with at leastone of the first port or the second port. The one or more bores in thenoise attenuating member are larger than pores of the porous material.

In another embodiment, the noise attenuating member includes one or morebores therethrough aligned for fluid communication with at least one ofthe first port or the second port. The fluid communication between thefirst port and the second port may include a secondary fluid flow patharound one or more outer sides of the noise attenuating member. Tofacilitate the flow path around one or more sides of the noiseattenuating member, the internal cavity may include a plurality ofsupport members extending from an interior bottom thereof upward intothe internal cavity to collectively define a first seat upon which thenoise attenuating member is seated. Also, the internal cavity mayinclude a plurality of positioning members. The plurality of positioningmembers are typically each longer than each of the plurality of supportmembers, and are positioned to be juxtaposed to the sound attenuatingmember. Furthermore, the plurality of support members may be spacedapart from one another to define a plurality of pathways for fluid flowunderneath the noise attenuating member.

In one embodiment, the noise attention member is disposed within theinternal cavity at a position spaced apart from interior walls of theinternal cavity and thereby defines a fluid flow passage between thenoise attenuating member and the interior walls, which is in fluidcommunication with the plurality of pathways underneath the noiseattenuating member. The interior bottom beneath the noise attenuatingmember may be generally shaped as an interior of one-half of a horntorus when viewed as a transverse cross-section.

In another embodiment, the noise attenuating member is dimensioned for atight fit within the housing thereby defining only fluid flow throughthe sound attenuating member. In this embodiment, the noise attenuatingmember may include a hollow portion therein having an open first end anda closed second end. The hollow portion has larger pores than that ofthe porous material defining the noise attenuating member. In oneembodiment, the hollow portion is generally cone-shaped and may bedefined by a plurality of stacked plugs, one of which has a depressionand the others having bores therethrough.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front, perspective view of a sound attenuation unitconnectable to become part of a fluid flow path.

FIG. 2 is a longitudinal, cross-sectional view of the sound attenuationunit of FIG. 1.

FIG. 3A is a top, perspective view of one embodiment of a soundattenuating member having a central bore therethrough.

FIG. 3B is a top, perspective view of a porous sound attenuating member.

FIG. 3C is a top plan view of another embodiment of a sound attenuatingmember having a plurality of bores therethrough.

FIG. 3D is a top, perspective view of one embodiment of a soundattenuating member having a central bore that is conical orfunnel-shaped.

FIG. 3E is a top, perspective view of one embodiment of a soundattenuating member having a recess therein.

FIG. 4 is a front perspective view of a second embodiment of a soundattenuation unit connectable to become part of a fluid flow path.

FIGS. 5A and 5B are top plan views of the sound attenuation unit of FIG.4, but with the first port in alternate positions relative to the secondport.

FIG. 6 is a front, perspective view of a sound attenuation unit similarto FIG. 4, but with an alternate upper portion having a first port of astraight configuration.

FIG. 7 is a longitudinal, cross-sectional view of the sound attenuationunit of FIG. 4.

FIG. 8 is a top plan view into the bottom portion of the soundattenuation unit of FIG. 4 with the sound attenuating member seatedtherein.

FIG. 9 is a top plan view of an alternate bottom portion of the soundattenuation unit of FIG. 4 without the sound attenuating member seatedtherein.

FIG. 10 is a longitudinal, cross-sectional view of an embodiment of asound attenuation unit that has a plurality of porous sound attenuatingmembers stacked therein.

DETAILED DESCRIPTION

The following detailed description will illustrate the generalprinciples of the invention, examples of which are additionallyillustrated in the accompanying drawings. In the drawings, likereference numbers indicate identical or functionally similar elements.

As used herein, “fluid” means any liquid, suspension, colloid, gas,plasma, or combinations thereof.

FIG. 1 is an external view of a noise attenuating unit, generallyidentified by reference number 10, for use in an engine, for example, ina vehicle's engine. The engine may be an internal combustion engine, andthe vehicle and/or engine may include a device requiring a vacuum. Checkvalves and/or aspirators are often connected to an internal combustionengine before the engine throttle and after the engine throttle. Theengine and all its components and/or subsystems are not shown in thefigures, and it is understood that the engine components and/orsubsystems may include any components common to an internal combustionengine. The brake boost system is one example of a subsystem that can beconnected to an aspirator and/or check valve. In another embodiment, anyone of a fuel vapor purge system, exhaust gas recirculation system, acrankcase ventilation system and/or a vacuum amplifier may be connectedto an aspirator and/or check valve. The fluid flow within the aspiratorand/or check valves, in particular when a Venturi portion is included,is generally classified as turbulent. This means that in addition to thebulk motion of the fluid flow, such as air or exhaust gases, there arepressure waves traveling through the assembly and different naturalfrequencies can become excited, thereby resulting inturbulence-generated noise. The noise attenuation unit 10 disclosedherein attenuates such turbulence-generated noise.

Referring to FIGS. 1 and 2, the noise attenuation unit 10 may bedisposed in, and thereby becomes part of, any fluid flow path(s) withinan engine in need of noise attenuation, and is typically positioned inthe flow path downstream of the source of the noise. The noiseattenuating unit 10 includes a housing 14 defining an internal cavity 16enclosing a noise attenuating member 20 therein. The noise attenuatingmember 20 typically fits securely within the internal cavity sandwichedbetween a first seat 26 and a second seat 28. The housing defines afirst port 22 in fluid communication with the internal cavity 16 and asecond port 24 in fluid communication with the internal cavity 16. Theexterior surfaces of the housing 14 that define the first and secondports 22, 24 both include fitting features 32, 34 for connecting thenoise attenuating unit 10 into a fluid flow path of the engine. Forexample, in one embodiment both fitting features 32, 34 are insertableinto a hose or conduit and the fitting features provide a securefluid-tight connection thereto.

The housing 14, as shown in FIG. 2, may be a multiple piece housing witha plurality of pieces connected together with a fluid-tight seal. Themultiple pieces may include a first housing portion 50 that includes thefirst port 22 and a male end 23 and a second housing portion 52 thatincludes the second port 24 and a female end 25. The male end 23 isreceived in the female end 25 with a sealing member 18 therebetween toprovide a fluid-tight seal between the portions 50, 52. In otherembodiments, the first housing portion 50 and the second housing portion52 have a container and cap type construction such as shown in FIG. 4and described below.

In FIG. 2, the noise attenuating member 20 is dimensioned for a tightfit within the housing and thereby the fluid flow through the internalcavity 16 is only available through the sound attenuating member 20itself and any bores it may include.

In the embodiment of FIG. 2, the first port 22 and the second port 24are positioned opposite one another to define a generally linear flowpath through the noise attenuation unit 10, but are not limited to thisconfiguration. In another embodiment, the first and second ports 22, 24may be positioned relative to one another at an angle of less than 180degrees, which may include configurations similar to FIGS. 4-6.

Referring to FIG. 2, the sound attenuating member 20 is porous such thatfluid flow through the unit 10 is restricted the least amount possible,but sound (turbulence-generated noise) is attenuated. The porous soundattenuating member 20 can be made from a variety of materials includingmetals, plastics, ceramics, or glass. The sound attenuating members maybe made from wire, woven or matted, sintered particles, fibers woven ormatted, but are not limited thereto. The porous character of the soundattenuating members causes the noise pressure waves to attenuate byinterfering with themselves, but should be of sufficient size and shapeto not unduly restrict or interfere with fluid flow, for example, airflow through the system. In one embodiment, the sound attenuatingmembers are not harmed (do not deteriorate) by operating temperatures ofan engine based on placement of the unit in the engine system.Additionally, the sound attenuating members are not harmed by thevibrations experienced during operating conditions of the engine.

As shown in FIG. 3B, the porous sound attenuating member may be acontinuous plug of porous material, generally identified by thereference number 30, with the only passageways therethrough beingchannels defined by its natural porosity, i.e., no enlarged bore holesare present, such as those shown in FIGS. 3A, 3C and 3D. The continuousplug may be any shape and configuration to fit within the cavity 16 ofthe sound attenuating unit 10, but as illustrated may be disc-shaped.

As shown in FIG. 3A, the porous sound attenuating member 20 includes onebore hole 21, but as shown in FIG. 3C, a second porous sound attenuatingmember 40 may include more than one bore hole 42. The bore holes providethe benefit of minimizing unwanted bulk flow restriction within thesound attenuating unit 10. The bore holes 21, 42 may be circular incross-section and define a regular cylindrical hole therethrough asshown in FIG. 3A or define a funnel-shaped hole 55 therethrough as shownin the porous sound attenuating member 20′ of FIG. 3D, but are notlimited thereto. In another embodiment, the bore holes 21, 42 may beelliptical or polygonal in cross-section. The hole's axis(es) will begenerally parallel to the direction of flow in or out of at least one ofthe first port 22 or the second port 24.

As shown in FIG. 3A, if a single bore hole 21 is present, it may begenerally centrally positioned within the sound attenuating member 20,but is not limited thereto. The dimensions of the bore hole 21 aretypically smaller than the internal dimensions of the first port 22, butare not limited thereto. When the bore hole 21 is circular incross-section, the diameter of the bore hole 21 may be about 8 mm toabout 14 mm. As shown in FIG. 3C, a plurality of bore holes 42 arepresent and are symmetrically positioned relative to one another withinthe porous sound attenuating member 20. These bore holes 42 may becircular in cross-section as shown, but are not limited thereto. Asdescribed for FIG. 3A, hereto the dimensions of the bore holes 42 aresmaller than the internal dimensions of the first port 22. When boreholes 42 are circular in cross-section, the diameter of each may beabout 3 mm to about 5 mm.

Alternately or in addition to a bore hole through the porous soundattenuating member, one of the major surfaces of a sound attenuatingmember may include a depression therein, preferably the major surfacefacing upstream. For example, the porous sound attenuating member 20″ ofFIG. 3E includes a depression 56. The depression 56 may be cone-shapedas best seen in FIG. 10. In another embodiment, the depression 56 may befunnel-shaped or any other shape suitable for attenuating the turbulentnoise within the system.

Now referring to FIGS. 4-9, other embodiments of sound attenuating units100 (FIG. 4), 100′ (FIG. 6) and alternate components thereof areillustrated. Beginning with FIG. 4 and the longitudinal cross-sectionthereof in FIG. 7, a noise attenuation unit 100 connectable to becomepart of a fluid flow path is shown as including a housing 114 definingan internal cavity 116 and having a first port 122 and a second port 124each connectable to a fluid flow path (not shown) and in fluidcommunication with one another through the internal cavity 116. Seatedwithin the internal cavity 116 is a noise attenuating member 120, whichis seated within the pathway of the fluid communication between thefirst port 122 and the second port 124. The noise attenuating member 120allows fluid to flow therethrough from the first port to the second portor vice versa and attenuates sound.

The noise attenuation member 120 may be shaped and made of the materialsdiscussed above with respect to FIGS. 2-3E.

The housing 114 as shown in FIG. 4 may be a multiple piece housing witha plurality of pieces connected together with a fluid-tight seal. Themultiple pieces may include a first housing portion 150 that includesthe first port 122 and a second housing portion 152 that includes thesecond port 124. In FIG. 4, the first housing portion 150 is generallycap-shaped and closes the generally cup- or bowl-shaped second housingportion 152 with a fluid-tight seal. While no sealing member is shownseated between the first housing portion 150 and the second housingportion 152, one may be included as described above. The exteriorsurfaces of the first and second ports 122, 124 both include fittingfeatures 132, 134 for connecting the noise attenuating unit 100 into afluid flow path. For example, in one embodiment both fitting features132, 134 are insertable into a hose or conduit and the fitting featuresprovide a secure fluid-tight connection thereto.

As shown in FIG. 4, one or more of the first port 122 and the secondport 124 include an elbow. Here, the first port 122 on the cap-shapedfirst housing portion 150 includes the elbow 160. This first housingportion 150 is positionable for attachment to the second housing 150portion with the elbow 160 oriented at any angle in a 360 degree radiusrelative to the second port 124. As shown in FIG. 4, the first port 122is oriented 180 degrees, and opens in a direction opposite, from thesecond port 124. In FIG. 5A, the first port 122 is oriented at 90degrees relative to the second port 124. In FIG. 5B, the first port 122is oriented at about 60 degrees relative to the second port 124. Theseembodiments are merely examples of possible orientations for the firstport 122 relative to the second port 124, which include myriadpossibilities in the 360 degrees about which the first housing portion150 may be rotated and then fixed to the second housing portion 152.

As shown in FIG. 4, the first port 122, which includes the elbow 160,enters the internal cavity 116 from the top (or may enter from thebottom) of the housing 114 and the second port 124 enters from a side ofthe housing 114. As shown in FIG. 6, the sound attenuating unit 100′includes an alternate first housing portion 150′ that has a straightfirst port 122′ extending therefrom. The straight first port 122′ entersthe internal cavity 116 from the top (or may enter from the bottom) ofthe housing 114′ and the second port 124 enters from a side of thehousing 114′. As shown in FIG. 9, a second housing portion 152′ having asecond port 124′ entering from the side may have the second port 124′offset from the center of the second housing portion 152′. In FIG. 9,because the second housing portion 152′ defining the internal cavity 116is generally circular from a top plan view, the second port 124′ isaligned with a chord of this generally circular shape. The position ofthe second port 124′ in FIG. 9 may in some systems provide improvednoise attenuation and/or reduce the amount of pressure drop experiencedas fluid flows through the sound attenuating unit.

Now referring to FIGS. 7-9, the internal cavity 116, which is primarilydefined by the second housing portion 152, 152′, includes a plurality ofsupport members 162 (FIGS. 7 and 9) extending from the interior bottom164 thereof upward into the internal cavity 116, 116′ to collectivelydefine a first seat 126 upon which the noise attenuating member 120 isseated. The plurality of support members 162 are spaced apart from oneanother to define a plurality of pathways 163 (FIG. 9) for fluid flowunderneath the noise attenuating member 120, i.e., between the noiseattenuating member 120 and the interior bottom 164 of the second housingportion 152, 152′.

The internal cavity 116, 116′ also includes a plurality of positioningmembers 166 (FIGS. 8 and 9). Each of the plurality of positioningmembers 166 are longer than each of the plurality of support members 162and are spaced apart from one another about the sound attenuating member120 in positions juxtaposed thereto to hold the sound attenuating member120 in place at a distance spaced apart from the interior wall(s) 168 ofthe second housing portion 150, 152′. Accordingly, a fluid flow passage169 is defined between the noise attenuating member 120 and the interiorwall(s) 168 providing fluid communication between the first port 122 andthe second port 124 through this secondary fluid flow path around one ormore outer sides of the noise attenuating member. The fluid flow passage169 is in fluid communication with the plurality of pathways 163underneath the noise attenuating member 120. The plurality ofpositioning members 166 are typically positioned at positions that arenot within the flow path leading to and from the second port 124 toavoid inducing any additional turbulence in the fluid flow.

As can be seen in FIGS. 7-9, the interior bottom 164 of the secondhousing portion 152, 152′ may be contoured to enhance the fluid flowthrough the sound attenuation unit 100, 100′ and to reduce a pressuredrop as well. In the illustrated embodiments, the interior bottom 164beneath the noise attenuating member 120 is generally shaped as theinterior of one-half of a horn torus when viewed as a transversecross-section, which is generally centered under a sound attenuatingmember 120 that includes one bore 121 therethrough. In embodiments wherethe sound attenuating member does not include a bore or has a pluralityof bores, such as shown in FIGS. 3B and 3C, other contours for theinterior bottom 164 of the second housing portion 152, 152′ will be morebeneficial as can be appreciated by one of skill in the art to enhancefluid flow and reduce the pressure drop.

In each of the embodiments disclosed herein, the fluid flow may be inthrough the first port and out through the second port or the oppositethereof. With reference to FIG. 7, this concept is shown by the arrowslabeled as “Fluid.” When the first port 122 is the inlet fluid, thesound is typically entering the sound attenuating unit 100 from thesecond port 124, which is designated as “Sound₁.” Conversely, when thesecond port 124 is the inlet for the fluid, the sound typically entersfrom the first port 122, which is designated as “Sound₂.” In the soundattenuating unit 100 of FIG. 7, the inclusion of the plurality ofsupport members 162 to define the plurality of pathways 163 and thedimensions of the sound attenuating unit 120 to define the fluid flowpassage 169 provides the advantage of increased surface area contact ofthe sound with the sound attenuating member 120. In FIG. 7, the surfacearea S is labeled. Here, the sound can contact the outer surface 172,the inner surface 174 and the bottom surface 176 of the soundattenuating member 120. In comparison, the sound in the embodiment ofFIG. 2 has less surface area S to contact when using an equivalentlysized sound attenuating member, which includes the inner surface andpossibly a portion of the upper surface and/or lower surface. To providethe same amount of surface area in the embodiment of FIG. 2, the overalldimensions of the sound attenuating unit 10 would be required to belarger. Thus, one advantage of the embodiments of FIGS. 4-9 is anoverall smaller package, which may be easier to fit within a fluid flowpath in an engine.

Another difference in the embodiments of FIG. 2 and FIG. 7 is that thepassage straight through the sound attenuating unit 10 of FIG. 2provides a minimal pressure drop in the fluid flow as it passestherethrough, whereas the fluid flow through the sound attenuating unit100 of FIG. 7 experiences a pressure drop. Depending on the use of theparticular sound attenuation unit, either may be desirable. However, asshown in FIG. 7, features such as the contour of the interior bottom 164underneath the sound attenuating member 120, increased dimensions forthe bore 121 through the sound attenuating member 120, a larger innerdimension for the first port 122 or the second port 124 relative to theother (such as D₁ compared to D₂), the presence of the fluid flowpassage 169, or any combination thereof may be introduced to reduce orminimize the pressure drop as fluid flows through the sound attenuatingunit 100.

Turning now to FIG. 10, another embodiment for a noise attenuation unit10′ is illustrated that has many similar features to those of FIGS. 1and 2. As such, like reference numbers are repeated in FIG. 10. Thenoise attenuation unit 10′ includes a housing 14 defining an internalcavity 16 enclosing a plurality of noise attenuating members 20′, 20′a,and 20″. The noise attenuating members 20′, 20′a, and 20″ typically fitsecurely within the internal cavity in a stacked relationship relativeto one another such that the plurality are sandwiched between a firstseat 26 and a second seat 28 defined by the housing 14. Collectively asshown in FIG. 10, the plurality of sound attenuating members 20′, 20′a,and 20″ are stacked such that the combination of bores and depression(s)therein form a generally cone- or funnel-shaped bore that may passcompletely therethrough or at least partially therethrough. Tocollectively form such a shape, the uppermost sound attenuating member20′ (uppermost is relative to the orientation of the illustration on thepage) has a funnel-shaped bore that is generally larger than thefunnel-shaped bore of the middle sound attenuating member 20′a and thelowermost sound attenuating member 20″ has a cone- or funnel-shaped boreor depression that is dimensionally smaller than the bore of the middlesound attenuating member 20′a. Each of the plurality of soundattenuating members 20′, 20′a, and 20″ are dimensioned such that, whenstacked, there is a smooth gradual taper from the wide end 60 of theoverall bore or depression to the narrower end 62.

The housing defines a first port 22 in fluid communication with theinternal cavity 16 and a second port 24 in fluid communication with theinternal cavity 16. The exterior surfaces of the housing 14 that definethe first and second ports 22, 24 both include fitting features 32, 34for connecting the noise attenuating unit 10 into a fluid flow path ofthe engine. For example, in one embodiment both fitting features 32, 34are insertable into a hose or conduit and the fitting features provide asecure fluid-tight connection thereto.

The housing 14, as shown in FIG. 10, may be a multiple piece housingwith a plurality of pieces connected together with a fluid-tight seal.The multiple pieces may include a first housing portion 50′ thatincludes the first port 22 and a female end 27 and a second housingportion 52′ that includes the second port 24′ and a male end 29. Themale end 29 is received in the female end 27 to provide a fluid-tightseal between the portions 50, 52.

In FIG. 10, the noise attenuating members 20′, 20′a, and 20″ aredimensioned for a tight fit within the housing and thereby the fluidflow through the internal cavity 16 is only available through the soundattenuating members and any bores that may be included therein.

In the embodiment of FIG. 10, the first port 22 and the second port 24′are positioned opposite one another to define a generally linear flowpath through the noise attenuation unit 10, but are not limited to thisconfiguration. The sound attenuating members 20′ 20′a, and 20″ aretypically made of a porous material as described above.

Having described the invention in detail and by reference to specificembodiments thereof, it will be apparent that numerous modifications andvariations are possible without departing from the spirit of theinvention as defined by the following claims.

What is claimed is:
 1. A noise attenuation unit connectable to a fluidflow path of an engine comprising: a housing consisting essentially of afirst housing portion defining a first port and a second housing portiondefining a second port, the first housing portion and the second housingportion are mated together with a fluid-tight seal to define an internalcavity in fluid communication with the first port and the second port;and a porous noise attenuating material dimensioned for a tight fitwithin the internal cavity and seated therein, the porous noiseattenuating material comprising a plurality of stacked plugs of porousmaterial, wherein one of the plurality of stacked plugs has a boretherethrough and one has a bore partially therein that is larger thanpores of the porous material, and the combination thereof is stacked toform a hollow portion in general alignment with the first port and thesecond port; wherein fluid flow from the first port to the second portthrough the internal cavity is only through the porous noise attenuatingmaterial wherein the bore therethrough or the bore partially therein areeach larger than pores of the porous material.
 2. The noise attenuationunit of claim 1, wherein the first port and the second port are alignedopposite one another and the porous noise attenuating material issandwiched between a first seat of the first housing portion and asecond seat of the second housing portion.
 3. The noise attenuation unitof claim 2, wherein one or more of the first port and the second portinclude an elbow.
 4. The noise attenuation unit of claim 1, wherein oneof the first housing portion and the second housing portion defines acontainer for the noise attenuating member and the other thereof definesa cap for the container.
 5. The noise attenuation unit of claim 1,further comprising a sealing member seated between the first housingportion and the second housing portion to provide the fluid-tight sealtherebetween.
 6. The noise attenuation unit of claim 1, wherein the borehas a diameter of about 3 mm to about 5 mm.
 7. The noise attenuationunit of claim 1, wherein the bore partially therein defines a hollowportion that is generally cone-shaped.
 8. The noise attenuation unit ofclaim 1, wherein the bore has a diameter of about 3 mm to about 5 mm. 9.The noise attenuation unit of claim 1, wherein the hollow portion isgenerally cone- or funnel-shaped.
 10. The noise attenuation unit ofclaim 1, wherein the porous noise attenuating material is made fromwoven wire, matted wire, sintered particles, woven fibers, or mattedfibers of metal, plastic, ceramic, or glass.
 11. The noise attenuationunit of claim 10, wherein the porous noise attenuating material is inthe shape of a plug.
 12. A fluid flow system of an internal combustionengine comprising: a device for generating vacuum comprising a Venturiportion and/or a check valve; and a noise attenuation unit of claim 1positioned downstream of the Venturi device and/or the check valve. 13.The fluid flow system of claim 12, wherein the porous noise attenuatingmaterial is made from woven wire, matted wire, sintered particles, wovenfibers, or matted fibers of metal, plastic, ceramic, or glass.